According to a blog post and a report by "The Economist", Ted Cruz defeated Donald Trump in the primary in Wisconsin. Cruz received 48% of the votes, and Trump received 35%. His loss in Wisconsin means that Trump will likely not obtain the 1237 delegates that he needs to clinch the Republican nomination for president.
Nonetheless, he still has a high probability of becoming the president via a 3rd-party candidacy in November -- if Bernie Sanders does not run as a 4th-party candidate. Many Americans want Trump to be their president. According to an op-ed in "USA Today", he is popular among even highly educated Americans.
Going forward, what should Trump do? He should continue the campaign. After he is denied the nomination in the Republican convention, he leaves the Republican party and takes his supporters (at least, 45% of the Republican party) to the exits. He promptly files the paperwork to become the write-in candidate in all 50 states.
What should we -- the regular folks -- do? We write "Donald Trump" on the ballot for president. Furthermore, we write "Donald Trump" on the ballot for all the congressional races having Republican candidates who tried to derail the campaign of Trump. Such Republican candidates include John McCain of Arizona and Lindsey Graham of South Carolina.
Also, we write "Donald Trump" on the ballot for the gubernatorial races having Republican candidates who tried to derail the campaign of Trump. Such Republican candidates include Scott Walker of Wisconsin and Nikki Haley of South Carolina.
On the other hand, if Trump actually supports the Republican nominee and refuses to become a 3rd-party candidate, then he would be admitting that he has been a liar and a fraud. In that case, we vote for Bernie Sanders.